1. Field of the Invention
This invention relates to a mattress pad particularly adopted to prevent decubitus ulcers of a bedridden person wherein the mattress pad utilized polyurethane foam of differing stiffnesses.
2. Description of the Prior Art
Mattress pads of convoluted polyurethane foam such as disclosed in U.S. Pat. No. 3,258,791 have been known and used for many years. In such a case the convolutions extend over the entire top surface of the mattress pad and the peaks of the convolutions are all generally co-planar as are the bottom of the valleys between the peaks. The difficulty with such structure is that the stiffness or density of the foam is the same over the entire area with no particular effort to consider the weightier part of a body such as the torso. Certain areas of the body have a tendency to compress the peaks more than others so that there is really no airspace between the body and the mattress. Such a situation would foster decubitus ulcers (bed sores) of bedridden patients instead of prevention of the same.
In U.S. Pat. No. 3,604,025 the foam bedding for box spring and mattress use does have areas of differential resistance to weight. However, there are no convolutions for the passage of air and thus decubitus ulcers are not prevented.
Turning now to U.S. Pat. No. 4,620,337 this convoluted foam mattress also does not solve the problem. In this patent there are convoluted ends for the head and feet and the ends taper upwardly. The upward taper appears to be required to present more material so that the convolutions are not flattened all the way. As for the center section of the mattress there are a plurality of ribs that extend between the end portions. However, there is no indication that the density or stiffness of the center section differs from the end sections to present a firmer area for the torso. The entire mattress pad is of a single piece construction with the same density of foam throughout. Such construction does not truly lend itself to complete prevention of decubitus ulcers.